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It is evident from the informations presented above, that differentiation of alpha-amylase isozymes into malt type and green type have taken place in the very early stage of, or before differentiation of Gramineae, that is the dual genetic system of two types of alpha-amylase isozymes, which was confirmed at first in wheat and its relatives (Nishikawa et al 1989, Furuta et al unpublished) is a characteristics common to the whole family. One more important aspect is that there are more or less intraspecific genetic variations in amylase isozymes in this family, especially in Triticinae. In addition, common wheat and oat, hexaploid species, have triplicate genetic system. Interspecific variation and polyploidy no doubt result in the considerable genetic variation of alpha- and beta-amylase isozymes. Nishikawa and Nobuhara (1971), Nishikawa et al (1975, 1980, 1988) analyzed the genetic variation of those isozymes in di- and tetraploid wheat as well as hexaploid wheat. In addition, diploid ancestral species of tetra- and hexaploid wheat were also analyzed. Based on these results, phylogeny of common and tetraploid wheat was discussed (Nishikawa et al 1980, 1992). Some of alpha-amylase loci were analyzed and mapped on the chromosomes of homoeologous groups 6 and 7 (Nishikawa et al 1981). On the other hand, the fewer studies comparable to those in wheat were reported in oat, corn and rice and of course in millet.

Huang et al (1992) compared DNA base sequences of alpha-amylase among rice, barley and wheat, and classified the genes into two families or three subfamilies and discussed about phylogeny of this enzyme in Gramineae. The present results at the enzyme level well consistent with data at DNA sequence level.


References

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Nishikawa K, Furuta Y and Wada T (1980) Genetic studies of alpha-amylase isozymes in wheat. III. Intraspecific variation in Aegilops squarrosa and birthplace of hexaploid wheat. Jpn J Genet 55: 325-336.

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Nishikawa K, Furuta Y, Hiraku T and Takayanagi M (1988) Variation and chromosome arm location of the genes for gibberellic acid induced isozymes (Genetic studies of alpha-amylase isozymes in wheat V.). Japan J Breed 38: 187-197.

Nishikawa K, Furuta Y, Yamada T and Kudo S (1992) Genetic studies of alpha-amylase isozymes in wheat. VII. Variation in diploid ancestral species and phylogeny of tetraploid wheat. Jpn J Genet 67: 1-15.

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Tateoka T (1959) The family Gramineae (in Japanese). Meibundo (Tokyo) pp.150.

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